Antidegradants impact thermal oxidative stability

Thermal aging resistance of vulcanizates can be characterized by monitoring several chemical changes. In addition to reversion of the sulfur network, oxidative aging will occur to both the polymer main chain and to the sulfur network. Collectively, these changes will have significant impact on the ultimate strength characteristics of the compound and, perhaps more significantly, the dynamic mechanical properties of the elastomer. The dynamic mechanical properties will characterize the elastomer performance in several critical areas and will influence properties such as heat buildup, traction, rolling resistance and damping characteristics. 

Previous studies have shown that compounds protected with quinonediimine antidegradants maintain significantly more polysulfidic crosslinks upon thermal aging than compounds protected with conventional antidegradants. This improvement in network maintenance can lead to improvements in dynamic mechanical
properties upon aging. In this paper, the thermal oxidative stabilities of various compounds protected with a variety of commercially available antidegradants are compared by various methods. Retention of physical properties (strength characteristics) will be compared along with the comparison of retained dynamic 
mechanical properties. Finally, these properties will be rationalized by the analysis of the ability of the antidegradant system to preserve the sulfur network. Suggestions will be made regarding the best choice of antidegradant systems in order to meet demanding service conditions. 



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Nguồn: Quốc Anh, Cao su Đức Minh
http://caosu.org/entry.php/109-Antidegradants-impact-thermal-oxidative-stability